DTP Tools recommends

Page Control for Adobe InDesign

€ 7.6get CC version€ 59buy CS3-CS6
The plug-in lets you create different page sizes and both vertical and horizontal spreads inside one InDesign document. One page could be Letter and another page could be A3, and next one could be the size of an envelope. Inserts, foldout and even spines can now be part of the same document file.

Page size can be assigned to a single page or spread or to a master page and all associated pages. There is no limit to how many different page sizes there are in the document.

New in 2.2: Each page size can have its own print preset assigned assuring the page will be printed from the correct tray or printer. With a single click your document can be sent to all printers in the office, each processing the page size it is best suited for. more about this feature here

Free reader for editing page control created documents is available for download.